Case 38

35 yo F no sig pmh presents for one day of vaginal bleeding worsening this AM with suprapubic pain without dysuria.  LMP 7 weeks ago, positive urine HCG at home.  Patient has not received any prenatal care.

Vitals:  T 98.4 F  BP 104/78  HR 109 O2 100% RA

On physical exam patient restless secondary to pain.  Tenderness to palpation in the suprapubic region.  Pelvic exam shows blood in the vaginal vault with closed cervix no CMT or adnexal tenderness.

Urine pregnancy positive.  Hgb stable, serum beta HCG pending.
You decide to send the patient for transvaginal ultrasound.


  1. What is your differential diagnosis?
  2. What is this finding called?
  3. What defines this finding on ultrasound?
  4. Why is this finding concerning?


  1. threatened abortion, completed abortion, ectopic pregnancy, interstitial ectopic pregnancy 
  2. Interstitial ectopic pregnancy
  3. An IUP less than 8 mm measured from edge of gestational sac to edge of myometrium (endomyometrial mantle - EMM) is concerning for an interstitial pregnancy and the patient needs close follow up.  Clinical discretion is advised on a case by case basis.  [An IUP with an EMM of less than 5mm is very concerning and OBGYN should be definitively notified in the ER.] 
  4. Interstitial ectopic pregnancies implant in the vascular rich area where the fallopian tube connects to the uterine wall (see image below).  Due to the adequate blood supply to the growing pregnancy, interstitial ectopic pregnancies rupture later in pregnancy and thus have a higher morbidity and mortality rate.

For further information on this topic, we recommend Dr. Resa Lewiss' discussion on The Ultrasound Podcast